1. Field of the Invention
The present invention relates generally to downhole electrical connectors for use in oil field applications. More specifically, the present invention relates to a pothead connector for connecting an insulted power cable to the motor of an electric submersible pump.
2. Description of the Related Art
Downhole electric submersible pumps are driven by electric motors. The electric motor is powered from the surface, so a cable must be fed down the well to the pump motor. Prior to lowering the motor, a motor lead of the cable is attached with what is known in the art as a pothead connector. The pothead connector secures the motor lead to the motor so that it is not loosened as it is lowered. The pothead connector must also be able to withstand the downhole environment, which may include caustic materials under high pressure and temperatures. The service life of the pothead connector depends on its ability to seal effectively.
Various sealing techniques and cable securing means have been used. Typically, a metal housing is used for the connector. An insulating block mounts inside the housing. The insulating block has passages for receiving the insulated conductors. Electrical contact pins are secured to each conductor and protrude from the forward side of the insulating block. Epoxy is filled in the spaces around the conductors within the housing to seal the conductors and secure them. The housing has an integral cylindrical lip that protrudes past the insulating block for reception in a mating receptacle.
In accordance with the present invention, a pothead connector is provided with a protective housing near the terminal end of a motor lead. In all of the embodiments, an insulating block is mounted in the housing. The insulating block has at least one hole therethrough for receiving an insulated electrical conductor. An electrical contact pin is secured to the conductor within the insulating block and protrudes from the insulating block. A cylindrical wall or lip is integrally formed on the insulating block and protrudes past a first end of the housing. A seal is located on the outer diameter of the lip.
In another embodiment, the insulating block has a counterbore in a second end. A second insulating block is also disposed within the protective housing. The second insulating block has a passage through which the insulated conductor passes. The second insulating block also has a protrusion on a lower face that is concentric with the counterbore and shaped to fit within the counterbore in the first-mentioned insulating block.
An elastomeric washer is positioned within the counterbore at the second end of the passage in the first insulating block. The elastomeric washer has a hole through which the insulated conductor passes. A fastener rigidly secures the second insulating block to the first insulating block, forcing the protrusion against the elastomeric washer to cause the washer to seal around the insulated conductor. The elastomeric washer will also effectively secure the insulated conductor in the protective housing.
The fastener may take the form of a shoulder engaging the second end of the second insulating block coupled with a retaining ring engaging the first insulating block. Alternatively the fastener may be a threaded connector between the two insulating blocks. A threaded connector could include a spring to compensate for thermal expansion.
In still another embodiment, the insulating block is formed of a thermoplastic material that is compatible with a thermoplastic insulating layer on the conductors. After installation in the holes, the insulating layer is heat fused to the insulating block.